I am certain this is an artifact of the implementation. I used to
work for a source control firm, whose product was based on the SCCS
file format. Both archive size and time to extract were always equal
to or better than local RCS. Time to check in a new version was
occasionally a bit slower than local RCS, but that was an artifact of
*that* implementation, and in any case checkin time is not nearly as
important.

> An alternative to consider is Josh McDonald's xdelta/xdfs.

I'm not familiar with these. Xdelta's big claim to fame was handling
binary files efficiently, yes? I remember being annoyed at some
version of PRCS because the archives were always binary - not just
because of the compression, either. In my opinion, if the data stored
in the file is 7-bit ASCII, the entire archive file should be 7-bit
ASCII. (With an option to compress the entire file on the fly.)